Glucose-insulin and potassium infusions in septic shock

Effect of Glucose-Insulin-Potassium Infusion on Hemodynamics in Patients with Septic Shock

BACKGROUND: Glucose-insulin-potassium (GIK) demonstrates a cardioprotective effect by providing metabolic support and anti-inflammatory action, and may be useful in septic myocardial depression. AIM: The aim of this study was to assess role of GIK infusion in improving hemodynamics in patients with septic shock in addition to its role in myocardial protection and preventing occurrence of sepsis-induced myocardial dysfunction and sepsis-induced arrhythmias. METHODS: This study was conducted on 75 patients admitted to the Critical Care Department in Cairo University Hospital with the diagnosis of septic shock during the period from January 2019 to December 2019. Patients were divided into two groups; first group was managed according to the last guidelines of surviving sepsis campaign and was subjected to the GIK infusion protocol while second group was managed following the last guidelines of surviving sepsis campaign only without adding GIK infusion. RESULTS: Patients in the GIK group showed better lactate clearance (50% vs. 46.7%) and less time needed for successful weaning of vasopressors than the control group (3.57±1.16 vs. 3.6±1.45 days) thought not reaching statistical significance. There was no statistically significant difference between both groups regarding development of septic-induced cardiomyopathy (16.7% in the control group vs. 13.3% in the GIK group); however, patients with hypodynamic septic shock showed better improvement in hemodynamic profile in the GIK group. Sepsis-induced arrhythmias occurred more in patients of the control group than in patients of the GIK group with no statistically significant difference between both groups (33.3% vs. 20%, p = 0.243). Few side effects were developed as a result of using GIK infusion protocol. CONCLUSIONS: GIK may help in improving hemodynamics and weaning of vasopressors in patients with refractory septic shock and those with septic induced cardiomyopathy. The use of GIK was well tolerated with minimal adverse reactions.

Glucose-insulin-potassium correlates with hemodynamic improvement in patients with septic myocardial dysfunction

BACKGROUND

Glucose-insulin-potassium (GIK) demonstrates a cardioprotective effect by providing metabolic support and anti-inflammatory action, and may be useful in septic myocardial depression. The aim of this study was to examine the relationship between GIK and hemodynamic outcomes in septic shock patients with myocardial depression.

METHODS

Between October 2012 and March 2014, 45 patients in the intensive care unit who fulfilled the criteria for severe sepsis/septic shock and were treated with GIK were recruited. Patients were divided into two groups according to echocardiographic findings: hypodynamic (27%) and non-hypodynamic (36%).

RESULTS

Baseline vasopressor requirements did not differ between both groups. In 12 patients with hypodynamic septic shock with myocardial depression, mean arterial pressure (MAP) increased with the median [interquartile range (IQR)] area under the curve of 16 (8 to 29) mmHg, and the heart rate (HR) decreased with the median (IQR) area under the curve of -9 (-20 to 2)/min during the first 72 h. The total insulin dose correlated with improvement in MAP (r=0.61, P=0.061) and the cardiovascular Sequential Organ Failure Assessment score (r=-0.64, P=0.045) at 72 h, although this phenomenon was not observed in patients with non-hypodynamic septic shock. Serum glucose and potassium levels were within the target ranges in both groups during the 72-h study period.

CONCLUSIONS

Short-term improvement in hemodynamics correlated with GIK administration in septic shock patients with myocardial depression. The use of GIK was well tolerated in all patients. Further studies are required to demonstrate the role of GIK in septic myocardial dysfunction.

Catecholamines for inflammatory shock: a Jekyll-and-Hyde conundrum

Catecholamines are endogenous neurosignalling mediators and hormones. They are integral in maintaining homeostasis by promptly responding to any stressor. Their synthetic equivalents are the current mainstay of treatment in shock states to counteract myocardial depression and/or vasoplegia. These phenomena are related in large part to decreased adrenoreceptor sensitivity and altered adrenergic signalling, with resultant vascular and cardiomyocyte hyporeactivity. Catecholamines are predominantly used in supraphysiological doses to overcome these pathological consequences. However, these adrenergic agents cause direct organ damage and have multiple 'off-target' biological effects on immune, metabolic and coagulation pathways, most of which are not monitored or recognised at the bedside. Such detrimental consequences may contribute negatively to patient outcomes. This review explores the schizophrenic 'Jekyll-and-Hyde' characteristics of catecholamines in critical illness, as they are both necessary for survival yet detrimental in excess. This article covers catecholamine physiology, the pleiotropic effects of catecholamines on various body systems and pathways, and potential alternatives for haemodynamic support and adrenergic modulation in the critically ill.

Use of insulin to decrease septic shock-induced myocardial depression in a porcine model

Insulin is known to attenuate septic shock-induced myocardial depression. Possible mechanisms include an anti-inflammatory or inotropic effect of insulin. The objective of this study was to determine whether the mechanism of action of insulin in attenuating septic shock-induced myocardial depression is through an immunomodulatory effect. Fourteen pigs were assigned to one of two groups. Both groups received a 4-h infusion of lipopolysaccharide endotoxin from Escherichia coli 0111:B4. Group 2 additionally received insulin at 1.5 U/kg/h with infusions of D50 normal saline and KCl to maintain normal serum glucose and potassium levels. Cardiac function was measured with shortening fraction using transthoracic echocardiogram. Plasma TNF-α, IL-1β, and IL-6 levels were obtained every 30 min. Postmortem cytokine analysis and histomorphology were performed on the heart tissue. Although insulin attenuated septic shock-induced myocardial depression, this was not due to an anti-inflammatory effect and, therefore, likely resulted from an inotropic effect of insulin.

Therapeutic strategies for high-dose vasopressor-dependent shock

There is no consensual definition of refractory shock. The use of more than 0.5 mcg/kg/min of norepinephrine or epinephrine to maintain target blood pressure is often used in clinical trials as a threshold. Nearly 6% of critically ill patients will develop refractory shock, which accounts for 18% of deaths in intensive care unit. Mortality rates are usually greater than 50%. The assessment of fluid responsiveness and cardiac function can help to guide therapy, and inotropes may be used if hypoperfusion signs persist after initial resuscitation. Arginine vasopressin is frequently used in refractory shock, although definite evidence to support this practice is still missing. Its associations with corticosteroids improved outcome in observational studies and are therefore promising alternatives. Other rescue therapies such as terlipressin, methylene blue, and high-volume isovolemic hemofiltration await more evidence before use in routine practice.

Cardiovascular and metabolic effects of high-dose insulin in a porcine septic shock model

OBJECTIVES

High-dose insulin (HDI) has inotropic and vasodilatory properties in various clinical conditions associated with myocardial depression. The authors hypothesized that HDI will improve the myocardial depression produced by severe septic shock and have beneficial effects on metabolic parameters. In an animal model of severe septic shock, this study compared the effects of HDI treatment to normal saline (NS) resuscitation alone.

METHODS

Ten pigs were randomized to an insulin (HDI) or NS group. All were anesthetized and instrumented to monitor cardiovascular function. In both arms, Escherichia coli endotoxin lipopolysaccharide (LPS) and NS infusions were begun. LPS was titrated to 20 mug/kg/hour over 30 minutes and continued for 5 hours, and saline was infused at 20 mL/kg/hour throughout the protocol. Dextrose (50%) was infused to maintain glucose in the 60-150 mg/dL range, and potassium was infused to maintain a level greater than 2.8 mmol/L. At 60 minutes, the HDI group received an insulin infusion titrated from 2 to 10 units/kg/hour over 40 minutes and continued at that rate throughout the protocol. Survival, heart rate (HR), mean arterial pressure (MAP), pulmonary artery and central venous pressure, cardiac output, central venous oxygen saturation (SVO(2)), and lactate were monitored for 5 hours (three pigs each arm) or 7 hours (two pigs each arm) or until death. Cardiac index, systemic vascular resistance (SVR), pulmonary vascular resistance (PVR), O(2) delivery, and O(2) consumption were derived from measured data. Outcomes from the repeated-measures analysis were modeled using a mixed-effects linear model that assumed normally distributed errors and a random effect at the subject level.

RESULTS

No significant baseline differences existed between arms at time 0 or 60 minutes. Survival was 100% in the HDI arm and 60% in the NS arm. Cardiovascular variables were significantly better in the HDI arm: cardiac index (p < 0.001), SVR (p < 0.003), and PVR (p < 0.01). The metabolic parameters were also significantly better in the HDI arm: SVO(2) (p < 0.01), O(2) delivery (p < 0.001), and O(2) consumption (p < 0.001). No differences in MAP, HR, or lactate were found.

CONCLUSIONS

In this animal model of endotoxemic-induced septic shock that results in severe myocardial depression, HDI is associated with improved cardiac function compared to NS resuscitation alone. HDI also demonstrated favorable metabolic, pulmonary, and peripheral vascular effects. Further studies may define a potential role for the use of HDI in the resuscitation of septic shock.

The role of protein O-linked beta-N-acetylglucosamine in mediating cardiac stress responses

The modification of serine and threonine residues of nuclear and cytoplasmic proteins by O-linked beta-N-acetylglucosamine (O-GlcNAc) has emerged as a highly dynamic post-translational modification that plays a critical role in regulating numerous biological processes. Much of our understanding of the mechanisms underlying the role of O-GlcNAc on cellular function has been in the context of its adverse effects in mediating a range of chronic disease processes, including diabetes, cancer and neurodegenerative diseases. However, at the cellular level it has been shown that O-GlcNAc levels are increased in response to stress; augmentation of this response improved cell survival while attenuation decreased cell viability. Thus, it has become apparent that strategies that augment O-GlcNAc levels are pro-survival, whereas those that reduce O-GlcNAc levels decrease cell survival. There is a long history demonstrating the effectiveness of acute glucose-insulin-potassium (GIK) treatment and to a lesser extent glutamine in protecting against a range of stresses, including myocardial ischemia. A common feature of these approaches for metabolic cardioprotection is that they both have the potential to stimulate O-GlcNAc synthesis. Consequently, here we examine the links between metabolic cardioprotection with the ischemic cardioprotection associated with acute increases in O-GlcNAc levels. Some of the protective mechanisms associated with activation of O-GlcNAcylation appear to be transcriptionally mediated; however, there is also strong evidence to suggest that transcriptionally independent mechanisms also play a critical role. In this context we discuss the potential link between O-GlcNAcylation and cardiomyocyte calcium homeostasis including the role of non-voltage gated, capacitative calcium entry as a potential mechanism contributing to this protection.

Insulin-dependent rescue from cardiogenic shock is not mediated by phospholamban phosphorylation

INTRODUCTION

We used immunoblots to determine whether inotropic and lusitropic effects of high-dose insulin (HDI) in cardiogenic shock, induced by a beta-blocker (BB) or a calcium channel blocker (CCB), are mediated by phosphorylation of phospholamban (PLB). PLB is a membrane protein that regulates calcium uptake into the sarcoplasmic reticulum (SR) by inhibition of the cardiac calcium pump (SERCA2a). Phosphorylation of PLB relieves SERCA inhibition, thus enhancing diastolic relaxation and preload.

METHODS

Our Institutional Animal Care and Use Committee approved this research. Swine myocardia from six groups were flash frozen immediately upon death or sacrifice. Groups 1-6 received: (1) no medications, (2) HDI and glucose only, (3) toxic propranolol infusions and saline resuscitation, (4) toxic propranolol infusions and HDI resuscitation, (5) toxic verapamil infusions and saline resuscitation, and (6) toxic verapamil infusions and HDI resuscitation. Groups 3-6 were resuscitated for 4 h. Tissue samples from all six groups were analyzed by quantitative immunoblots, using antibodies to both unphosphorylated PLB (uPLB) and phosphorylated PLB (pPLB), to determine the total PLB content and the fraction of PLB phosphorylated.

RESULTS

There were no differences in either pPLB or total PLB in cardiac tissue among any of the six groups. However, infusion of a pig with the beta-adrenergic agonist, isoproterenol, produced enhanced PLB phosphorylation.

CONCLUSION

The mechanism by which HDI produces its inotropic and lusitropic effects in CCB- and BB-induced cardiovascular toxicity, resulting in resuscitation, is not due to changes in phosphorylation of PLB or a change in the total PLB in the SR.

Effect of glucose-insulin-potassium infusion on mortality in critical care settings: a systematic review and meta-analysis

This study seeks to measure the treatment effect of glucose-insulin-potassium (GIK) infusion on mortality in critically ill patients. A systematic review of randomized controlled trials is conducted, comparing GIK treatment with standard care or placebo in critically ill adult patients. The primary outcome variable is mortality. Two authors independently extract data and assess study quality. The primary analysis is based on the random effects model to produce pooled odds ratios (ORs) with 95% confidence intervals (CIs). The search yields 1720 potential publications; 23 studies are included in the final analysis, providing a sample of 22,525 patients. The combined results demonstrate no heterogeneity (P=.57, I2=0%) and no effect on mortality (OR=1.02; 95% CI, 0.93-1.11) with GIK treatment. No experimental studies of shock or sepsis populations are identified. This meta-analysis finds that there is no mortality benefit to GIK infusion in critically ill patients; however, study populations are limited to acute myocardial infarction and cardiovascular surgery patients. No studies are identified using GIK in patients with septic shock or other forms of circulatory shock, providing an absence of evidence regarding the effect of GIK as a therapy in patients with shock.

HEXOSAMINE BIOSYNTHESIS AND PROTEIN O-GLYCOSYLATION

An early and rapid response to severe injury or trauma is the development of hyperglycemia, which has long been thought to be an essential survival response by providing fuel for vital organ systems and facilitating mobilization of interstitial fluid reserves by increasing osmolarity. However, glucose can also be metabolized via the hexosamine biosynthesis pathway (HBP), leading to the synthesis of uridine diphosphate N-acetyl-glucosamine(UDP-GlcNAc). UDP-GlcNAc is a substrate for the addition, via an O-linkage, of a single N-acetylglucosamine to serine or threonine residues of nuclear and cytoplasmic proteins (O-glycosylation, O-GlcNAc). There is increasing appreciation that protein O-glycosylation is a highly dynamic posttranslational modification that plays a key role in signal transduction pathways. Sustained increases in O-GlocNAc have been implicated in the development of diabetes and diabetic complications; however, recent studies have demonstrated that stress leads to a transient increase in O-GlcNAc levels that is associated with increased tolerance to stress. Indeed, activation of pathways leading to O-GlcNAc formation improves cell survival after I/R injury, whereas inhibition of O-GlcNAc formation decreases cell survival. In addition, in rodent models of trauma-hemorrhage, increasing O-GlcNAc levels during resuscitation improves cardiac function and organ perfusion and attenuates the inflammatory response. At the cellular level, increasing O-GlcNAc levels attenuates nuclear factor-kappaB activation. It is noteworthy that other metabolic-based treatments for severe injury such as glucose-insulin-potassium and glutamine also lead to increased HBP flux and O-GlcNAc levels. The goal of this review is to summarize our current understanding of the role of the HBP and O-GlcNAc on the regulation of cell function and survival and to present evidence to support the notion that activation of these pathways represents a novel treatment strategy for severe injury and trauma.